And the number of extinctions continues at a high rate in the twenty - first century.

灭绝物种的数量在 二十一 世纪仍在以很高的速率上涨.

超越目标英语 第3册

Perhaps, extinctions are caused by something outside, like comets and asteroids.

也许, 灭绝是由外来物体引起的, 比如彗星和小行星.

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Studies of fossils had pointed to five great extinctions in the past.

对化石的研究表明,历史上曾发生过5次大规模的物种灭绝.

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Scientists then began searching the layers of rocks delineate mass extinctions.

科学家们开始研究详细记录了大规模灭绝事件的岩石层.

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She said a major cause of the extinctions are plants and animals not native to Hawaii.

她说非夏威夷本土的动植物引入是促使物种灭绝的主要原因.

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Therefore, some climate change or other environmental factor must have caused the species'extinctions.

因此, 一定是一些气候上的变化或其他环境因素导致了这些物种的灭绝.

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So, if you lose a key species, you might cause a whole flood of other extinctions.

所以, 如果失去了一种关键物种, 那么有可能导致一连串其他物种的灭绝.

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